Identification and characterisation of incompatibility factors in Hamelia patens Jacq. (Rubiaceae)

Summary

Hamelia patens Jacq., commonly called firebush, is a fast-growing, semi-woody, evergreen, perennial shrub in the family Rubiaceae. It is native to central southern Florida, USA and is cultivated on a wider scale as an ornamental plant in home gardens of India. From previous analyses, it was found that sexual reproduction in H. patens was limited due to self-incompatibility and was overcome by intraspecific pollination between morphologically different accessions. Diffusion plate assays, spectrophotometric analysis, and in vitro bioassays were conducted to measure RNase activity among stigma proteins. After compatible cross-pollination, the RNase activity was less than during incompatible pollination. RNase activity was present in extracts as well as leachates of the stigma. Diffusion plate assays and spectrophotometric assays were used to measure the RNase activity. In vitro assays revealed that RNase activity was essential for the inhibition of pollen tube growth. Our study confirmed that RNase-based gametophytic self-incompatibility operates in H. patens.